Here's the interesting part: exercise improved people's feelings about their body even if they didn't lose weight or achieve noticeable improvements. They just felt better about it.

Body weight, shape and body image were assessed in 16 males and 18 females before and after both 6 × 40 mins exercise and 6 × 40 mins reading. Over both conditions, body weight and shape did not change. Various aspects of body image, however, improved after exercise compared to before, while no changes were found over reading. These findings have implications for exercise promotion where a possible role for body image in exercise adherence is suggested, and confirm current theories of body image, where changes in body image are mediated by body perceptions as opposed to actual body indices.

Source: "6 X 40 Mins Exercise Improves Body Image, Even Though Body Weight and Shape do not Change" from Journal of Health Psychology